Names of Family members in English:
1. Grandmother - दादी/नानी,
2. Grandfather - दादा/नाना
3. Grandparent - दादा/दादी/नाना/नानी
To be specific:
Paternal Grandfather - दादा
Paternal Grandmother - दादी
Maternal Grandmother - नानी
Maternal Grandfather - नाना
We generally use the word 'Grandparent' to refer to दादा/दादी/नाना/नानी.
4. Granddaughter - पोती/नाती
5. Grandson - पोता/नाता
6. Grandchild - नाता/नाती/पोता/पोती
7. Aunt - चाची/ताई/फूफी/बुआ/मामी/मौसी
For example: She is my aunt (not: She is my aunty)
8. Uncle - चाचा/ताऊ/फूफा/मामा/मौसा/काका
9. Niece - भतीजी/भांजी
10. Nephew - भतीजा/भांजा
11. Cousin - चचेरा ममेरा मौसेरा या फुफेरा भाई या बहन
Tip: We don't need to say 'Cousin Brother' or 'Cousin Sister' - just 'cousin' is enough. For example: She is my cousin (not: She is my cousin sister)
12. Sister - in - law - ननद/भाभी
13. Brother - in - law - देवर/जेठ
14. Mother - in - law - सास
15. Father - in - law - ससुर